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package javax.xml.parsers;

import javax.xml.validation.Schema;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;

/**
 * Defines a factory API that enables applications to configure and
 * obtain a SAX based parser to parse XML documents.
 *
 * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
 * @author <a href="mailto:Neeraj.Bajaj@sun.com">Neeraj Bajaj</a>
 * @version $Revision: 1.9 $, $Date: 2010/05/25 16:19:44 $
 */
public abstract class SAXParserFactory {

  /**
   * <p>Should Parsers be validating?</p>
   */
  private boolean validating = false;

  /**
   * <p>Should Parsers be namespace aware?</p>
   */
  private boolean namespaceAware = false;

  /**
   * <p>Protected constructor to force use of {@link #newInstance()}.</p>
   */
  protected SAXParserFactory() {

  }

  /**
   * Obtain a new instance of a <code>SAXParserFactory</code>. This
   * static method creates a new factory instance
   * This method uses the following ordered lookup procedure to determine
   * the <code>SAXParserFactory</code> implementation class to
   * load:
   * <ul>
   * <li>
   * Use the <code>javax.xml.parsers.SAXParserFactory</code> system
   * property.
   * </li>
   * <li>
   * Use the properties file "lib/jaxp.properties" in the JRE directory.
   * This configuration file is in standard <code>java.util.Properties
   * </code> format and contains the fully qualified name of the
   * implementation class with the key being the system property defined
   * above.
   *
   * The jaxp.properties file is read only once by the JAXP implementation
   * and it's values are then cached for future use.  If the file does not exist
   * when the first attempt is made to read from it, no further attempts are
   * made to check for its existence.  It is not possible to change the value
   * of any property in jaxp.properties after it has been read for the first time.
   * </li>
   * <li>
   * Use the service-provider loading facilities, defined by the
   * {@link java.util.ServiceLoader} class, to attempt to locate and load an
   * implementation of the service using the {@linkplain
   * java.util.ServiceLoader#load(java.lang.Class) default loading mechanism}:
   * the service-provider loading facility will use the {@linkplain
   * java.lang.Thread#getContextClassLoader() current thread's context class loader}
   * to attempt to load the service. If the context class
   * loader is null, the {@linkplain
   * ClassLoader#getSystemClassLoader() system class loader} will be used.
   * </li>
   * <li>
   * Otherwise the system-default implementation is returned.
   * </li>
   * </ul>
   *
   * Once an application has obtained a reference to a
   * <code>SAXParserFactory</code> it can use the factory to
   * configure and obtain parser instances.
   *
   *
   *
   * <h2>Tip for Trouble-shooting</h2>
   * <p>Setting the <code>jaxp.debug</code> system property will cause
   * this method to print a lot of debug messages
   * to <code>System.err</code> about what it is doing and where it is looking at.</p>
   *
   * <p> If you have problems loading {@link SAXParser}s, try:</p>
   * <pre>
   * java -Djaxp.debug=1 YourProgram ....
   * </pre>
   *
   * @return A new instance of a SAXParserFactory.
   * @throws FactoryConfigurationError in case of {@linkplain java.util.ServiceConfigurationError
   * service configuration error} or if the implementation is not available or cannot be
   * instantiated.
   */

  public static SAXParserFactory newInstance() {
    return FactoryFinder.find(
                /* The default property name according to the JAXP spec */
        SAXParserFactory.class,
                /* The fallback implementation class name */
        "com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl");
  }

  /**
   * <p>Obtain a new instance of a <code>SAXParserFactory</code> from class name.
   * This function is useful when there are multiple providers in the classpath.
   * It gives more control to the application as it can specify which provider
   * should be loaded.</p>
   *
   * <p>Once an application has obtained a reference to a <code>SAXParserFactory</code>
   * it can use the factory to configure and obtain parser instances.</p>
   *
   *
   * <h2>Tip for Trouble-shooting</h2>
   * <p>Setting the <code>jaxp.debug</code> system property will cause
   * this method to print a lot of debug messages
   * to <code>System.err</code> about what it is doing and where it is looking at.</p>
   *
   * <p> If you have problems, try:</p>
   * <pre>
   * java -Djaxp.debug=1 YourProgram ....
   * </pre>
   *
   * @param factoryClassName fully qualified factory class name that provides implementation of
   * <code>javax.xml.parsers.SAXParserFactory</code>.
   * @param classLoader <code>ClassLoader</code> used to load the factory class. If
   * <code>null</code> current <code>Thread</code>'s context classLoader is used to load the factory
   * class.
   * @return New instance of a <code>SAXParserFactory</code>
   * @throws FactoryConfigurationError if <code>factoryClassName</code> is <code>null</code>, or the
   * factory class cannot be loaded, instantiated.
   * @see #newInstance()
   * @since 1.6
   */
  public static SAXParserFactory newInstance(String factoryClassName, ClassLoader classLoader) {
    //do not fallback if given classloader can't find the class, throw exception
    return FactoryFinder.newInstance(SAXParserFactory.class,
        factoryClassName, classLoader, false);
  }

  /**
   * <p>Creates a new instance of a SAXParser using the currently
   * configured factory parameters.</p>
   *
   * @return A new instance of a SAXParser.
   * @throws ParserConfigurationException if a parser cannot be created which satisfies the
   * requested configuration.
   * @throws SAXException for SAX errors.
   */

  public abstract SAXParser newSAXParser()
      throws ParserConfigurationException, SAXException;


  /**
   * Specifies that the parser produced by this code will
   * provide support for XML namespaces. By default the value of this is set
   * to <code>false</code>.
   *
   * @param awareness true if the parser produced by this code will provide support for XML
   * namespaces; false otherwise.
   */

  public void setNamespaceAware(boolean awareness) {
    this.namespaceAware = awareness;
  }

  /**
   * Specifies that the parser produced by this code will
   * validate documents as they are parsed. By default the value of this is
   * set to <code>false</code>.
   *
   * <p>
   * Note that "the validation" here means
   * <a href="http://www.w3.org/TR/REC-xml#proc-types">a validating
   * parser</a> as defined in the XML recommendation.
   * In other words, it essentially just controls the DTD validation.
   * (except the legacy two properties defined in JAXP 1.2.)
   * </p>
   *
   * <p>
   * To use modern schema languages such as W3C XML Schema or
   * RELAX NG instead of DTD, you can configure your parser to be
   * a non-validating parser by leaving the {@link #setValidating(boolean)}
   * method <code>false</code>, then use the {@link #setSchema(Schema)}
   * method to associate a schema to a parser.
   * </p>
   *
   * @param validating true if the parser produced by this code will validate documents as they are
   * parsed; false otherwise.
   */

  public void setValidating(boolean validating) {
    this.validating = validating;
  }

  /**
   * Indicates whether or not the factory is configured to produce
   * parsers which are namespace aware.
   *
   * @return true if the factory is configured to produce parsers which are namespace aware; false
   * otherwise.
   */

  public boolean isNamespaceAware() {
    return namespaceAware;
  }

  /**
   * Indicates whether or not the factory is configured to produce
   * parsers which validate the XML content during parse.
   *
   * @return true if the factory is configured to produce parsers which validate the XML content
   * during parse; false otherwise.
   */

  public boolean isValidating() {
    return validating;
  }

  /**
   * <p>Sets the particular feature in the underlying implementation of org.xml.sax.XMLReader. A
   * list of the core features and properties can be found at <a href="http://www.saxproject.org/">http://www.saxproject.org/</a></p>
   *
   * <p>All implementations are required to support the {@link javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING}
   * feature. When the feature is</p> <ul> <li> <code>true</code>: the implementation will limit XML
   * processing to conform to implementation limits. Examples include entity expansion limits and
   * XML Schema constructs that would consume large amounts of resources. If XML processing is
   * limited for security reasons, it will be reported via a call to the registered {@link
   * org.xml.sax.ErrorHandler#fatalError(SAXParseException exception)}. See {@link SAXParser}
   * <code>parse</code> methods for handler specification. </li> <li> When the feature is
   * <code>false</code>, the implementation will processing XML according to the XML specifications
   * without regard to possible implementation limits. </li> </ul>
   *
   * @param name The name of the feature to be set.
   * @param value The value of the feature to be set.
   * @throws ParserConfigurationException if a parser cannot be created which satisfies the
   * requested configuration.
   * @throws SAXNotRecognizedException When the underlying XMLReader does not recognize the property
   * name.
   * @throws SAXNotSupportedException When the underlying XMLReader recognizes the property name but
   * doesn't support the property.
   * @throws NullPointerException If the <code>name</code> parameter is null.
   * @see org.xml.sax.XMLReader#setFeature
   */
  public abstract void setFeature(String name, boolean value)
      throws ParserConfigurationException, SAXNotRecognizedException,
      SAXNotSupportedException;

  /**
   * <p>Returns the particular property requested for in the underlying
   * implementation of org.xml.sax.XMLReader.</p>
   *
   * @param name The name of the property to be retrieved.
   * @return Value of the requested property.
   * @throws ParserConfigurationException if a parser cannot be created which satisfies the
   * requested configuration.
   * @throws SAXNotRecognizedException When the underlying XMLReader does not recognize the property
   * name.
   * @throws SAXNotSupportedException When the underlying XMLReader recognizes the property name but
   * doesn't support the property.
   * @see org.xml.sax.XMLReader#getProperty
   */
  public abstract boolean getFeature(String name)
      throws ParserConfigurationException, SAXNotRecognizedException,
      SAXNotSupportedException;


  /**
   * Gets the {@link Schema} object specified through
   * the {@link #setSchema(Schema schema)} method.
   *
   * @return the {@link Schema} object that was last set through the {@link #setSchema(Schema)}
   * method, or null if the method was not invoked since a {@link SAXParserFactory} is created.
   * @throws UnsupportedOperationException When implementation does not override this method
   * @since 1.5
   */
  public Schema getSchema() {
    throw new UnsupportedOperationException(
        "This parser does not support specification \""
            + this.getClass().getPackage().getSpecificationTitle()
            + "\" version \""
            + this.getClass().getPackage().getSpecificationVersion()
            + "\""
    );
  }

  /**
   * <p>Set the {@link Schema} to be used by parsers created
   * from this factory.</p>
   *
   * <p>When a {@link Schema} is non-null, a parser will use a validator
   * created from it to validate documents before it passes information
   * down to the application.</p>
   *
   * <p>When warnings/errors/fatal errors are found by the validator, the parser must
   * handle them as if those errors were found by the parser itself.
   * In other words, if the user-specified {@link org.xml.sax.ErrorHandler}
   * is set, it must receive those errors, and if not, they must be
   * treated according to the implementation specific
   * default error handling rules.
   *
   * <p>A validator may modify the SAX event stream (for example by
   * adding default values that were missing in documents), and a parser
   * is responsible to make sure that the application will receive
   * those modified event stream.</p>
   *
   * <p>Initialy, <code>null</code> is set as the {@link Schema}.</p>
   *
   * <p>This processing will take effect even if
   * the {@link #isValidating()} method returns <code>false</code>.
   *
   * <p>It is an error to use
   * the <code>http://java.sun.com/xml/jaxp/properties/schemaSource</code>
   * property and/or the <code>http://java.sun.com/xml/jaxp/properties/schemaLanguage</code>
   * property in conjunction with a non-null {@link Schema} object.
   * Such configuration will cause a {@link SAXException}
   * exception when those properties are set on a {@link SAXParser}.</p>
   *
   * <h4>Note for implementors</h4>
   * <p>
   * A parser must be able to work with any {@link Schema}
   * implementation. However, parsers and schemas are allowed
   * to use implementation-specific custom mechanisms
   * as long as they yield the result described in the specification.
   * </p>
   *
   * @param schema <code>Schema</code> to use, <code>null</code> to remove a schema.
   * @throws UnsupportedOperationException When implementation does not override this method
   * @since 1.5
   */
  public void setSchema(Schema schema) {
    throw new UnsupportedOperationException(
        "This parser does not support specification \""
            + this.getClass().getPackage().getSpecificationTitle()
            + "\" version \""
            + this.getClass().getPackage().getSpecificationVersion()
            + "\""
    );
  }

  /**
   * <p>Set state of XInclude processing.</p>
   *
   * <p>If XInclude markup is found in the document instance, should it be
   * processed as specified in <a href="http://www.w3.org/TR/xinclude/">
   * XML Inclusions (XInclude) Version 1.0</a>.</p>
   *
   * <p>XInclude processing defaults to <code>false</code>.</p>
   *
   * @param state Set XInclude processing to <code>true</code> or <code>false</code>
   * @throws UnsupportedOperationException When implementation does not override this method
   * @since 1.5
   */
  public void setXIncludeAware(final boolean state) {
    if (state) {
      throw new UnsupportedOperationException(" setXIncludeAware " +
          "is not supported on this JAXP" +
          " implementation or earlier: " + this.getClass());
    }
  }

  /**
   * <p>Get state of XInclude processing.</p>
   *
   * @return current state of XInclude processing
   * @throws UnsupportedOperationException When implementation does not override this method
   * @since 1.5
   */
  public boolean isXIncludeAware() {
    throw new UnsupportedOperationException(
        "This parser does not support specification \""
            + this.getClass().getPackage().getSpecificationTitle()
            + "\" version \""
            + this.getClass().getPackage().getSpecificationVersion()
            + "\""
    );
  }
}
